1. Field of the invention
The invention relates to a resin. Particularly, the invention relates a strippable adhesive composition and uses thereof. When applying the strippable adhesive composition in soldering an electrical device on a printed circuit board or in spraying or plating a printed circuit board, the strippable adhesive composition can protect the surface can be mechanically strippable and removal after the procedure.
2. Description of the Related Art
Generally, the strippable adhesive composition for protecting the surface when soldering the electronic device on the printed circuit board commonly has the following two major purposes: (1) in the flow soldering process (by directly contacting the printed circuit board with the molten solder bath), the strippable adhesive composition mainly protects the parts where the flux or solder are not easily attached, such as the terminal, contact, or variable resistor; (2) in the reflow soldering process (by welding with the melting solder at a high temperature after temporarily fixing the electronic device), in order to protect the wire part or terminal from oxidation, the strippable adhesive composition avoids the impedance increasing and the pollution of the contact materials caused by oxidized or carbonized surface of the metal such as copper and gold, even at the high temperature of welding. Furthermore, after such operations, the strippable adhesive composition can be easily stripped with the mechanical equipments such as clamps.
To achieve the aforementioned purposes, the thermoplastic type of strippable adhesive composition mainly comprising polyvinylchloride and a plasticizer are now widely used in the field. In the manufacturing the strippable adhesive composition, the polyvinylchloride powder is dispersed in the plasticizer to form a paste, the paste is coated on the desired part through wire screen printing or brushing, and then heated at 100° C. to 150° C. for a few minutes to several tens of minutes, and the a film by fusing polyvinylchloride and the plasticizer is obtained.
Among the various thermoplastic resins, although polyvinylchloride has good heat resistance and is inexpensive, it is accompanied by dehydrochlorination and then decomposition when exposed to 240° C. to 270° C. for a long period of time. Such phenomenon not only causes resin discoloration, but also causes burning-out on the circuit board due to increased hardness and brittle and difficult stripping.
To solve these problems, an optimized additive plasticizer or stabilizer is generally used. However, even the stability of the polyvinylchloride film is improved in this way, the stripability is still poor after heat treatment. Therefore, the stripping must be performed immediately after welding to avoid poor stripability.
In another aspect, the viscosity of the polyvinylchloride powder dispersed in the plasticizer is difficult to be controlled, and it leads poor coating properties such as uneven surfaces and irregular line when applying the composition by screen printing or brushing. Furthermore, the thin film obtained by the following heating step cannot meet the requirement in the modern field.
Therefore, overcoming the problems of poor stripability and coating properties to meet the current requirements is the target in the field of the present invention.